1. Field of the Invention
This invention relates to an apparatus for determining machining steps and a numerical control apparatus having a numerical control information generating function which generates information for numerical control prior to machining, and more particularly, to an apparatus which automatically revises the types of machining steps, the tools to be used and the scope of a machining process, which have been automatically determined previously, according to operator preferences.
2. Description of the Prior Art
Numerical control information generating functions have been put into practice which generate numerical control information such as NC (numerical control) programs from design drawings using a graphic display screen and from the inputting of necessary data through man-machine dialogue. An operator can input a machining shape simply by pressing keys on a keyboard which correspond to the shape of a part depicted in the design drawings. Such functions are also capable of graphically displaying reference information useful for setting data for each operation and for inputting various data such as dimensions in response to queries made using ordinary language. As soon as the necessary data have been inputted for the numerical control information generation, a blank shape and a part shape will be displayed on the screen instantly, automatic calculation of the numerical control data will be started, and tool paths will be graphically displayed to generate numerical control information.
The above mentioned function generally includes the following steps (a) through (j).
(a) a step to select blank material PA1 (b) a step to select graphic mode PA1 (c) a step to input a blank shape and its dimensions PA1 (d) a step to input a machined shape and its dimensions PA1 (e) a step to input machine original points and of a tool rest position PA1 (f) a step to select the type of steps PA1 (g) a step to select tools PA1 (h) a step to decide the scope of machining PA1 (i) a step to input cutting conditions PA1 (j) a step to calculate tool path
Necessary data are sequentially inputted to eventually generate numerical control information.
In the numerical control information generating system like the one mentioned above, after the blank shape and part shape have been inputted, an operator judges and decides which region of the blank will be machined by which type of machining steps, and in which direction a tool should be moved as well as the order of machining steps. The data are inputted in the order decided by the operator.
The prior art method is quite flexible as it allows an operator to freely set the order of the machining steps or the scope of machining, but it requires a skilled operator to do so. Unskilled operators cannot quite manage the process of setting those data and find such work to be very cumbersome. The conventional method is problematic further in that the inputting operation takes much time because the name of a step is first selected, the order of the steps is decided, and then the tools, the cutting direction, the scope of machining and the cutting conditions for each step are inputted.
In order to overcome those defects, there has been proposed an apparatus having a function which automatically decides the types of steps, the order of steps and the scope of machining based on the input blank shape, part shape and their dimensions. However, the step types and the machining scopes depend considerably on the knowhow of the particular operator and the tools to be used. If the data are automatically selected according to a uniform rule, they may not quite satisfy the requirements of the operator, and the operator more often than not will want to revise the step types, the tools to be used, and the scope of machining. Then, the dimensions have to be inputted again. This proposed apparatus could not quite solve the conventional problems nor eliminate troublesome steps.